Practice Essentials

Ebstein anomaly is a congenital malformation of the heart that is characterized by apical displacement of the septal and posterior tricuspid valve leaflets, leading to atrialization of the right ventricle with a variable degree of malformation and displacement of the anterior leaflet.

Signs and symptoms

Patients can have a variety of symptoms related to the anatomic abnormalities of Ebstein anomaly and their hemodynamic effects or associated structural and conduction system disease, including the following:

Diagnosis

Physical findings in patients with Ebstein anomaly span a spectrum from subtle to dramatic. They may include the following:

Cyanosis and clubbing

Precordial asymmetry

Jugular venous pulse

Arterial pulses: Usually normal but are diminished late in the disease course

Heart sounds: Widely split first heart sound with loud tricuspid component and soft/absent mitral component in the presence of prolonged PR interval; usually normal second heart sound but may be widely split when pulmonary component delayed due to right bundle-branch block; third and fourth heart sounds commonly present, even in the absence of congestive heart failure

Testing

A 12-lead electrocardiogram may demonstrate the following findings in patients with Ebstein anomaly:

Management

Treatment of Ebstein anomaly is complex and dictated mainly by the severity of the disease itself and the effect of accompanying congenital structural and electrical abnormalities. Treatment options include medical therapy, radiofrequency ablation, and surgical therapy.

Radiofrequency ablation of the accessory pathways is an alternative to medication for treatment of arrhythmias. Curative therapy of supraventricular tachycardia with radiofrequency ablation is the treatment of choice. However, in patients without significant structural heart disease, the success rate of this procedure is lower.

Surgical option

Surgical intervention includes the following:

Correction of the underlying tricuspid valve and right ventricular abnormalities

Correction of any associated intracardiac defects

Palliative procedures in early days of life as a bridge to more definitive surgical treatment later

Background

Ebstein anomaly is a congenital malformation of the heart that is characterized by apical displacement of the septal and posterior tricuspid valve leaflets, leading to atrialization of the right ventricle with a variable degree of malformation and displacement of the anterior leaflet.

Wilhelm Ebstein first described a patient with cardiac defects typical of Ebstein anomaly in 1866. In 1927, Alfred Arnstein suggested the name Ebstein's anomaly for these defects. In 1937, Yates and Shapiro described the first case of the anomaly with associated radiographic and electrocardiographic data.

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Pathophysiology

The embryological development of tricuspid valve leaflets and chordae involves undermining of the right ventricular free wall. This process continues to the level of the atrioventricular (AV) junction. In Ebstein anomaly, this process of undermining is incomplete and falls short of reaching the level of the AV junction. In addition, the apical portions of the valve tissue, which normally undergo resorption, fail to resorb completely. This results in distortion and displacement of the tricuspid valve leaflets, and a part of the right ventricle becomes atrialized. In one study involving 50 hearts with the anomaly, the entire right ventricle was found to be morphologically abnormal.
[1]

The hemodynamic consequences of Ebstein anomaly result from displaced and malformed tricuspid leaflets and atrialization of the right ventricle. The leaflet anomaly leads to tricuspid regurgitation. The severity of regurgitation depends on the extent of leaflet displacement, ranging from mild regurgitation with minimally displaced tricuspid leaflets to severe regurgitation with extreme displacement.

The atrialized portion of the right ventricle, although anatomically part of the right atrium, contracts and relaxes with the right ventricle. This discordant contraction leads to stagnation of blood in the right atrium. During ventricular systole, the atrialized part of the right ventricle contracts with the rest of the right ventricle, which causes a backward flow of blood into the right atrium, accentuating the effects of tricuspid regurgitation.

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Etiology

Ebstein anomaly is a congenital disease of often uncertain cause.

Environmental factors implicated in etiology include the following maternal factors
[2] :

Maternal ingestion of lithium in first trimester of pregnancy

Maternal benzodiazepine use

Maternal exposure to varnishing substances

Maternal history of previous fetal loss

The risk of having Ebstein anomaly is higher in white persons than in other races.

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Epidemiology

Ebstein anomaly probably accounts for 0.5% of cases of congenital heart diseases. Its true prevalence is unknown because mild forms frequently are undiagnosed. With the wide application of echocardiography, more cases are being diagnosed.

Race-, sex-, and age-related demographics

Ebstein anomaly is more common in children of white females. However, no specific sex predominance exists.

Ebstein anomaly can present at various stages of life, as follows:

Fetal life: Ebstein anomaly is usually diagnosed incidentally by echocardiography.

Septal leaflet attachment ratio (ie, ratio of distance between AV ring and distal attachment of septal leaflet to length of septal leaflet) of more than 0.45

Increasing ratio of combined area of right atrium and atrialized right ventricle to that of the functional right ventricle—grade 1, which is less than 0.5, to grade 4, which is more than 1.5 (increase in the relative risk of 2.7 for each increment in the grade)

New York Heart Association (NYHA) class: This has been linked with mortality rate in some studies
[6]

Morbidity/mortality

The natural course of the disease varies according to the severity of tricuspid valve displacement. Patients presenting in infancy generally have severe disease and unfavorable prognosis.
[7, 8]

The mean age of presentation is in the middle teenage years. According to older observational data, approximately 5% of these patients survive beyond age 50 years. The oldest recorded patient lived to age 85 years.